To date, there are several widespread diseases that are often fatal and which generally involve a certain type of white blood cell that is responsible for orchestrating the immune system of the body. Among such diseases, included are two highly malignant cancers known as adult T-cell leukemia (ATL) and acquired immuno-deficiency syndrome (AIDS). These diseases not only infect the same type of white blood cell but further share another crucial feature in that they are all caused by a class of infectious agents known as retroviruses.
Retroviruses are viruses that cannot replicate without controlling and exploiting the biosynthetic apparatus of a cell for different purposes. Retroviruses consist of the genetic material of RNA and are capable of reversing the ordinary flow of genetic information--from DNA to RNA to proteins. Additionally, retroviruses carry an enzyme called reverse transcriptase, which uses the viral RNA as a template for making DNA. The viral DNA integrates itself into the genome of the host wherein it remains latent until it is activated to make new virus particles. Much attention is being paid to the human immunodeficiency virus (HIV) retrovirus which causes AIDS due to its rapid transmission, progressive derangement of immune function and high fatality rate.
It appears that the HIV retrovirus enter a cell by binding to a molecule known as the CD4 antigen. The CD4 antigen is found primarily on specific set of white blood cells of the immune system called T4 lymphocytes or helper T cells. Accordingly, HIV infection is characterized by the loss of these T-lymphocyte cells, which causes a deterioration of the immune system.
The T-lymphocyte cell is crucial to the immune system in that, among other functions, it recognizes foreign antigens, or markers, on infected cells and helps to activate another set of lymphocyte white blood cells which multiply and produce antibodies that bind to infected cells. The T-lymphocyte cell further is capable of completely eliminating infected cells. Thus, the loss of T-lymphocyte cells not only seriously impairs the body's ability to fight most invaders, but also has a severe impact on the defenses against viruses, fungi, parasites and certain bacteria.
To date, there is no known cure for AIDS. There are presently various experimental drugs on the market including an antiviral substance known as azidothymidine (AZT) which has been shown to prolong the lives of certain AIDS patients. While AZT and other drugs have shown to be beneficial, they do not benefit all patients and accordingly, new solutions are needed. Moreover, the present drugs are for the most part extremely expensive and often difficult to obtain.
In the case of AIDS and some forms of hepatitis and leukemia, it is the secondary infections which are the actual cause of death. There is, therefore, a need for a means of treating such immune deficiency-causing diseases which boosts the suppressed lymphocyte levels and provides a defense against life-threatening secondary infections.